Fix some logic errors (requires testing)

src/datetime.rs

@@ -65,36 +65,36 @@ impl DateTime {
     /// Converts a Unix timestamp to a `DateTime` struct
     pub fn from_timestamp(ts: i64) -> Self {
         if ts < 0 {
-            let mut seconds: i64 = 0;
+            let mut seconds: i64 = ts;
-            let mut year = Year::new(-1);
+            let mut year = Year::new(1969);
-            while seconds > -year.seconds() {
+            while seconds < -year.seconds() {
-                seconds -= year.seconds();
+                seconds += year.seconds();
                 year = year.previous();
             }
             let mut month = Some(Month::December);
             while month.is_some() {
                 let m = month.unwrap();
-                if seconds > m.seconds(year) {
+                if seconds < -m.seconds(year) {
                     break;
                 }
-                seconds -= m.seconds(year);
+                seconds += m.seconds(year);
                 month = m.previous();
             }
             let month = month.unwrap();
             let mut day = month.days(year);
             while day > 0 && seconds < -SECONDS_PER_DAY {
-                seconds -= SECONDS_PER_HOUR;
+                seconds += SECONDS_PER_DAY;
                 day -= 1;
             }
             let mut hour: i8 = 23;
             while hour >= 0 && seconds < -SECONDS_PER_HOUR {
-                seconds -= SECONDS_PER_HOUR;
+                seconds += SECONDS_PER_HOUR;
                 hour -= 1;
             }
             let hour = hour.try_into().unwrap();
             let mut minute: i8 = 60;
             while minute >= 0 && seconds < -60 {
-                seconds -= 60;
+                seconds += 60;
                 minute -= 1;
             }
             let minute = minute.try_into().unwrap();